The invention relates to a valve means and more particularly an amplifier comprising a housing, which contains a movable switching element having two closure portions each associated with the opening of a fluid duct and engaged at two spaced points by two actuating diaphragms, which are able to be subject to fluid so that the switching element is able to be positioned in at least two switching positions in which the respectively one duct opening is closed and the respectively other duct opening is open.
Valve means of this type are customarily employed as pneumatic amplifiers, which are in a position to influence fluid flows with a high pressure and a high rate of flow using low control pressures. As far as the assignee is aware pneumatic amplifiers so far devised are characterized by having a plunger-like switching element having two closure portions adapted to close and open the opening of a respectively associated fluid duct in a manner dependent on the switching position of the switching element. The respective switching position is set by actuating diaphragms for engaging the switching element at two axially spaced points, and which as needed are subjected to a fluid acted upon by a control pressure. The switching over of valve means, which may be termed a diaphragm amplifier, takes place as part of a linear movement of the switching element.
It is considered to be a disadvantage of the valve means of this type that a reduction of the overall size and a standardization of the geometry thereof is only possible to a limited extent. The necessary arrangement of the ducts in the interior of the housing means that a certain minimum height is more or less necessary and can not be gone below. If various different amplifier functions are to be realized, then as a rule radical changes are necessary in the structure.
One object of the present invention is to create a valve means which has more compact dimensions and whose design is more readily adaptable.
In order to achieve this aim the switching element is constituted by a switching rocking member adapted to perform a pivotal movement on switching over, whose rocking arms placed on either side of the pivotal portion are engaged respectively by one of the actuating diaphragms and on which respectively one of the closure portions is provided.
It is in this manner that a valve means is provided, which may be manufactured with an extremely low, flat form, because on the one hand the actuating diaphragm and on the other hand the closure portions may be arranged, switching over no longer involving a linear movement but rather involves a pivoting or rocking movement of the rocker-like switching element which may consequently be termed a switching rocker member. The valve means may be employed in a relatively universal manner and is suitable, given a the correct geometry, more particularly as well in micro-actuators as a principal valve stage or in conjunction with other actuators as a high speed drive for valves having a large rated aperture or lumen. Moreover, the design in accordance with the invention favors a realization of the valve means in manufacturing methods in connection with micro-technology , because same are specifically suitable for the manufacture of flat, laminated structures. Finally the design of the invention favors the manufacture of valve means having different functions, because it is particularly in the case of an amplifier that there is the possibility of clearly separating the control plane and the power plane.
Further advantageous developments of the invention are defined in the dependent claims.
The switching rocker member and the actuating diaphragms are preferably accommodated in a common interior space in the housing. The housing itself may comprise several housing parts placed together as layers or lamellas, the two actuating diaphragms being held between the same housing parts.
The necessary pivotal movement of the rocking member could be predetermined exclusively by way of its attachment to the diaphragms, but however in order to ensure an exact switching function the invention preferably contemplates a pivotal support of the switching rocker member at its pivot portion.
A structure would be possible in which the actuating diaphragms only touch the switching rocker member. Presently a design is considered to be more convenient in which the actuating diaphragms are attached not only on the housing but also on the inherently rigid switching rocker member.
Both the actuating diaphragms and also the duct openings associated with the closure portions are preferably at least approximately at the same level as each other.
In order to produce an amplifier function in a particularly advantageous fashion there is preferably a provision such that the first and second fluid ducts associated with the closure portions and furthermore a third fluid duct communicate which are common connecting chamber, by way of which the fluid may be transferred, dependent on the switching position of the switching rocker member between the third fluid duct and one of the two other fluid ducts. Each of the two actuating diaphragms in this case preferably constitutes a movable wall between the connecting chamber and a control chamber, the two control chambers being separated from one another and each communicating with a control duct, by way of which the action of fluid on them may be set. In the case of such a structure it is frequently possible to alter the manner of functioning simply by changing the arrangement of the connections of the ducts, and for instance different types of amplifiers may be realized, which normally set a closed position or normally set an open position.
The actuating diaphragms may be designed with the same or different areas and in different sizes, forms and cross sections, it being possible to provide for preset deflections in the force-free state in order to influence the switching position of the switching rocker member.
The closure portions may be integrated in the switching rocker member or be in the form of separately applied sealing bodies.
In the case of the two actuating diaphragms it may be a question of individual diaphragms. However simpler manufacture and assembly is possible if the actuating diaphragms are united together in a common integral diaphragm element.
In what follows the invention will be described in detail with reference to the accompanying drawings.